This invention relates to a method of stimulating flow of particulates in a container or other enclosure.
A problem has existed for many years in maintaining uniform flow of particulates through a container. Coal, ore, sand, cement and other materials tend to jam and become impacted in a conical zone over the container outlet as is well known. This condition is variously referred to as bridging, caking or ratholing.
To alleviate this condition several things have been tried. Vibrators for shaking the container or its walls have been used. Air has been introduced to fluidize the particulates. And finally explosive injections of air have been tried when the material becomes completely blocked and will not flow. None of these has been truly effective in the sense of preventing blockage and maintaining uniform flow.
Another problem which sometimes occurs is that the particulates tend to adhere to the walls of the container. One example of this occurs in containers for handling moist materials in cold temperature environments. Frozen particulates tend to form on the cold walls and causes the particles to stick to them. Additional particles collect on those already frozen and build up to a point where removal is essential. It is known to apply heat externally to metal walls, but this is not practical where they are of thick concrete. Heating by electric panels or other internal means results in high installation and operating costs.
I have found an alternative which is effective for eliminating adhesion due to freezing conditions which is also effective for relieving bridging or ratholing.
It is known to provide resilient material covering the wall of a container and intermittently inflating and deflating the cover to dislodge bridged or caked materials. Such is described in West German Offenlegungschriften 2,249,858. However, there is no suggestion in that published patent application that the invention there disclosed would be effective for removing ice from container walls. Moreover, no such suggestion can be inferred from the disclosure therein since it is directed to alleviating caking of soft powdery materials. Also, the configuration used in the German application shows direct contact of the resilient inflatable material with the powder and holes in the container wall itself through which air is injected to inflate or balloon out the cover. Harder more abrasive materials would quickly puncture such a cover and render it useless.
It is also known to provide a loose plastic inflatable liner in the cavity of railroad hopper cars. This is shown in U.S. Pat. No. 2,931,523 Nelligan. However, the liner there disclosed is used to provide more storage space for material since it is used in a flat bottom type car. When inflated the liner bows out in an upward facing convex air causing the particles to roll downward toward the outlet.
Finally, it is known to provide bags of non-resilient material on walls of sand hoppers and to intermittently inflate and deflate then to relieve ratholing. Again, there has been no suggestion that such could be adapted to provide the additional function of separating frozen particulates or other weakly adherent particulates from the container wall.